MiR-21/Smad 7 signaling determines TGF-?1-induced CAF formation.

ABSTRACT: How TGF-?1-mediated signaling pathways are finely tuned to orchestrate the generation of carcinoma-associated fibroblasts (CAFs) is poorly understood. Here, we demonstrate that miR-21 and the signaling of its target Smad 7 determine TGF-?1-induced CAF formation. In primary cultured fibroblasts, mature miR-21 increases after TGF-?1 treatment, whereas the Smad 7 protein level decreases. MiR-21 binds to the 3' UTR of Smad7 mRNA and inhibits its translation, rather than causing its degradation. Most importantly, Smad 7 is bound to Smad 2 and 3, which are thought to competitively bind to TGFBR1, and prevents their activation upon TGF-?1 stimulation. The depletion of miR-21 or the overexpression of Smad 7 blocks TGF-?1-induced CAF formation, whereas the overexpression of miR-21 or the depletion of Smad 7 promotes CAF formation, even without TGF-?1 stimulation. Collectively, these findings clearly demonstrate that miR-21 and Smad7 are critical regulators of TGF-?1 signaling during the induction of CAF formation.

SUBMITTER: Li Q 

PROVIDER: S-EPMC3687228 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature